Charging circuit blows capacitor

Thread Starter


Joined Feb 1, 2020
Hello everybody,

I have a simple circuit from a charger which should charge my battery vacuum cleaner. Instead of 15V, charger was only giving 1.5V. When I dissasembled it, I noticed blown capacitor which I replaced with new one and I was careful about polarization. When I connected cirucuit back to electricity, new capacitor blew as well after few seconds. I presume one of other components failed as well. Which one is the most likely to be?

Thank you for help.


Thread Starter


Joined Feb 1, 2020
I checked both diodes with multimeter and it looks like they are ok, only letting current in one direction. Is there possibility one of them is faulty anyway?
I also checked the resistors and the two big ones should be 56 ohms each, but my multimeter shows values 28 ohms each.
There are no smd elements on the other side of PCB.


Joined Jun 16, 2018
The resistors are likely in parallel which would make sense given your measurement. Replace the diode(s) and the capacitor and try again.

Delta Prime

Joined Nov 15, 2019
may I ask.What is the DC working voltage of your electrolytic capacitor?

I understand you only put in 1.5 volts in it

If you can take a photo of your entire setup plus the underside of that board.


Joined Nov 13, 2015
Assume the leads on the left are to the battery holder. What are the three sets of red/black on the right? One must be power in (where is that coming from, what is the applied voltage?) Second looks like an indicator LED, what about the third? How about a picture of the bottom of the board.

Or practice your skills and draw out a complete schematic of the circuit.


Joined Jul 29, 2019
In a power supply, the components that fail the most are the Diodes and Caps. Are you sure you replaced the new Cap with the correct polarity? Did you check the diode with a diode check on a meter or just an ohmmeter? Did you check the diode in both directions? To check the diode with an ohmmeter you may have to de-solder one side to get an accurate measurement. One side should block any reading and reversing the meter probe, the other side should show a reading. Think of a series circuit with a diode inline. If you meter across either side of the diode the ohmmeter will show continuity (in this case you are not really metering the diode at all). That is the reason to de-solder one side.